Let me suggest a set of useful tools to stay in your car
Must have tools
Keep the spare tyre in the car. Ensure the spare wheel is properly inflated. Look at the tyre pressure of the spare wheel at least once per month to make certain it is usually ready for use. Some cars have space-saver stepneys or spare wheels - where the wheel and tyre is from a different size from the other four that the car is running on. In such cases, the spare wheel shall be used just to reach a tyre shop instead of continuously or at high speeds.
All cars come with a jack as part of the standard tools on offer. Be sure you understand the location of the jack in the car and how to operate the jack. Some cars provide a standard scissors jack. Some have a bottle-jack. Yet others provide a hydraulic jack. The jack may be located in the spare wheel well, or under a passenger seat, or even in the engine bay depending on the kind of vehicle you have. Make sure you familiarize yourself with the location and operation of the jack. Some jacks fit only into specific jacking points on the vehicle - be sure you know the location of these points to raise the vehicle.
There have been times when motorists have a jack but no jack handle. The jack handle in a few cars is not stored along with the jack. It may be located under the rear seat for instance or clipped to the back of the seat, or perhaps in a slot in the boot. Some cars also have a jack handle that needs to be assembled first and fits in the tool kit.
If you´ve got a spare wheel, jack and jack handle, it´s of no use unless you have a wheel spanner handy. A wheel spanner is amongst the standard tools that the car contains and demands to be in the car at all times. Occasionally, when you´ve swapped your normal wheels for fancy alloy wheels with locking nuts, be sure you buy a wheel spanner that´s appropriate for the alloy wheel nuts that you have.
All cars contain a collection of spare fuses of various ratings for that critical components of the car. These fuses are usually located in the fuse box lid in the vehicle. Ensure you understand the location of your fuse box in a vehicle. You'll find usually two fuse boxes - a principal fuse box found in the engine bay near the battery and a secondary fuse box that has the user changeable fuses often located within the vehicle, near the driver´s side. It is normally just under the dashboard, although in some vehicles, you may have to open up a panel to access the fuse box.
It has been mandated by law in India to offer a set of spare headlamp bulbs with the vehicle. Make sure you keep the bulbs safely in a car. Although this law is not that strict in India, it happens to be an offence to drive with non-working headlamps.
Warning triangles in India are pretty redundant. Although all cars come with the warning triangle as part of the tools supplied with the car, people seldom use them, while some truckers use them to decorate their trucks. Placing a warning triangle at least 30 feet behind the car if its parked on the side of a busy highway is the right thing to do. The problem is it can get swiped or damaged by errant drivers especially in India. A green leafy twig sticking out of the vehicle is what is the local replacement for the swanky warning triangle in several parts! But if you have the triangle, make sure you deploy it as intended
While many modern cars have little that you can do, carmakers provide a simple set of tools consisting of a screwdriver and in some cases a spanner or two that can open most of the standard sized nuts and bolts used in the car. At times a screwdriver may be needed to open a panel to access the fuse box for instance. Keep this in the car at all times. If you like, you may buy a more elaborate tool set that as more spanners, pliers, allen keys and other tools that will help you tinker around more - but it´s not something carmakers would recommend you do.
Carmakers also supply a first-aid kit with the car that´s mandated by law. The first-aid kit usually has a bottle of antiseptic, some gauze, cotton and sticking plaster. While this is just a token kit, it would be good to carry a proper emergency first aid kit with essential medicines, in addition to what comes with the car. Make sure you check the expiry dates and change the medicines every now and then.
In addition to the tools offered by the carmaker, also carry a bottle with drinking water at all times in the car. If not for you personally, you can also use the water to refill the windscreen wash fluid or just to clean your hands after changing a spare wheel or poking about under the bonnet.